Page:Popular Science Monthly Volume 62.djvu/123

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117
THE MOTIVE POWER OF HEAT.
THE MOTIVE POWER OF HEAT.
By C. K. EDMUNDS,
JOHNS HOPKINS UNIVERSITY.

MR. ALFRED RUSSEL WALLACE, in his 'Wonderful Century,' describes those great material and intellectual achievements which especially distinguish the nineteenth century from any and all of its predecessors, and shows how fundamental is the change they have effected in our life and civilization. From a comparative estimate of the number and importance of these achievements, he concludes that not only was the century just passed superior to any one that had gone before, but that it must in its results be compared with the whole preceding historical period. It, therefore, marks the beginning of a new era of human progress.

There appears, however, upon looking back through the long, dark vista of human history, one step in material progress that seems to be really comparable with several steps of modern times. It was when fire was first utilized and became the servant and friend rather than the master and enemy of man. From that day to this, fire, in various forms and in ever-widening spheres of action, has been the greatest, the essential factor in that increase of man's power over nature, which has in turn been a chief means of developing what we term civilization. As Mr. Fernald, in his 'Gulf of Fire,'[1] points out, all men, however widely separated by millenniums of time and by utmost range of space, by mountains, deserts and oceans, by color, language and occupation, by custom and religion, all agree in this they make fire a servant and a friend. Mr. Fernald shows how the firebrand draws an impassable line between man and the brute creation, and graphically depicts the part played by the ancient element fire in aiding man along that upward path which, having entered, he had only to follow on to make the universe his own.

Steam engines in their infancy were known as 'fire' (i. e., heat) engines; and, in point of fact, the older term is the more correct, because the water or steam is used only as a convenient medium through which the form of energy which we call heat is made to perform the required mechanical operations. The claims of the steam engine (as locomotive, marine and stationary) to the greatest share in the marvelous material progress of the nineteenth century are too

  1. Harper's Monthly Magazine, July, 1902.